1. Department of Obstetrics and Gynecology, The Second Hospital of Jilin University, Changchun, Jilin 130041, P.R. China
2. Department of Urology, The Second Division of The First Hospital, Jilin University, Changchun, Jilin 130031, P.R. China
3. Siping Health School of Jilin Province, Siping, Jilin 136000, P.R. China